In various applications, a drive assembly may be utilized to provide rotational power to various components. In tracked vehicles, for example, a final drive assembly may be mounted to a frame of the vehicle in order to provide rotational power, at an output hub of the drive assembly to drive the tracks of the vehicles and thereby move the vehicles over terrain. Such a drive assembly may include motors (electrical or hydraulic, for example) for providing rotational power, and planetary drive systems including various gears for adjusting the speed of the rotational power output at the output hub.
Known designs for drive assemblies may exhibit various characteristics that result in relatively large manufacturing costs for the drive assemblies. For example, a prior art drive assembly may include a motor mounted at a first end of the drive assembly, and a housing at a second end of the drive assembly. The housing may be integrally formed with an output hub, which may be attached to an external device, such as a wheel or sprocket, in order to provide rotational power from the motor to the external device. A planetary gear set is coupled to the motor and is disposed within the housing in order to provide a speed reduction of various ratios to rotational power received from the motor. The planetary gear set includes a rotating planetary ring gear. Traditional applications of a rotating planetary ring gear utilize either a two-piece assembly wherein a steel ring gear is pressed along a full length of the ring gear into an adjacent cast or ductile iron, or steel housing, or utilize a one-piece housing manufactured out of gear steel, which in some applications will require the ring gear teeth to be shaper cut.
A drawback of the known two-piece assembly (cast or ductile iron housing plus steel ring gear) is that an external housing is required for the ring gear to be placed into, and a drawback of the one-piece housing is that shaper cutting the gear teeth is a relatively costly manner of making the gear teeth.